Nasal continuous positive airway pressure treatment: current realities and future

Nasal continuous positive airway pressure (CPAP) is a highly effective treatment for obstructive sleep apnea syndrome. The apnea/hypopnea index (AHI) is reduced 10-fold, but the patient dropout rate is up to 30%, and usage is typically < 5 hours per night. Titration, designed to make the best trade-off between effectiveness and side effects, is expensive. Autotitrating devices make this trade-off on a minute-by-minute basis, potentially reducing mean pressure delivery, reducing side effects, and increasing compliance. The aim of this study was to test the effectiveness of the AutoSet self-adjusting nasal CPAP system (ResMed, Sydney, Australia) in eliminating obstructive events and normalizing the arousal index. Forty-five subjects (41 males and 4 females with AHI) values of > 20/hour were recruited, with written informed consent. Subjects slept for a diagnostic night, followed by a treatment night, in the laboratory, using the AutoSet system with full polysomnographic monitoring of respiratory and sleep variables. Arousals were scored using ASDA criteria. Hypopneas were scored when there was a 50% reduction in ventilation for > 10 seconds, associated with a 4% drop in oxygen saturation. For comparison, the ASDA arousal index in 16 normal subjects (without nasal CPAP) is provided. Results are given as mean +/- standard error of the mean. AHI was reduced from 55 +/- 3 to 1.5 +/- 0.35 events/hour (p < 0.0001). The arousal index was reduced from 65 +/- 3 to 18 +/- 2 events/hour (p < 0.0001), identical to the value in the 16 healthy normal subjects. There was a 158% +/- 21% increase in slow-wave sleep (p = 0.01) and a 186% +/- 27% increase in rapid eye movement sleep (p = 0.013). The AutoSet self-adjusting nasal CPAP system adequately treats obstructive sleep apnea syndrome on the first night under laboratory conditions.